how do i plot this?

x(t)=summation(k=1)^infinity . [(-1)]^(k-1).(2A/k.pi).sin(k.pi.t)

Answer 1

[Matt Fig]

What is A?

Try this:

function x = inf_sum(t,A)
k = 1:200;
[k,t] = meshgrid(k,t);
x = ((-1).^(k-1).*((2*A)./(k*pi)).*sin(k.*pi.*t));
x = sum(x,2);

Then from the command-line you do this:

A = 4;
t = 0:.1:10;
plot(t,inf_sum(t,A))

I have a feeling, however, that your A is a Fourier Coefficient, thought you seem to leave no confirmation of this. If that is true you will also need to calculate A in the function.